# Quantum Mechanics

~Three physicists were instrumental: Heisenberg, De Broglie, and Schrodinger ~Their approach stemmed from De Broglie's matter wave concept known as "Wave Mechanics" or "Quantum Mechanics" ~ Bohr's model was inefficient for atoms other than hydrogen or poly-electronic atoms ~ This new approach to a model of the atom focused on the concept of wave functions ~ Since electrons are particles and therefore have wave properties ~ Schrodinger viewed the electron as a standing wave

~ Standing waves must have whole numbers of half wavelengths in any motion ~ As an electron, this means that the hydrogen atoms could only have certain circular orbits with a circumference that whole number of wavelengths will fit. ~ All other orbits would be destructive in nature and would not exist ~ Schrodinger's mathematical work is simplified to : HΨ = EΨ ~ Ψ is called the wave function with the coordinates of its 3d space position ~ A wave function is called an orbital (this is not the Bohr orbit) ~ The Hydrogen electron in a 1s orbital is not moving around the nucleus in a circular orbit ~ It is still unknown how electrons are moving

1. Principle Quantum Number

~ represented by the letter "n"

~ it can only have positive integer values

~ n determines the size of the orbital

~ it is the energy level in the electron configuration

2. Angular Momentum Quantum Number

~ represented by the letter "l"

~ it has values from 0 to n-1

~ l is the sub-level and shape in the electron configuration l=0=s

l=1=p

l=2=d

l=3=f

l=4=g

l=5=h

etc.

3. Magnetic Quantum Number

~ represented by ml

~ it has values between -l and l

~ ml is the orbital

~ it is the probability of where the electrons are; however, the electron is there only 90% of the time

4. Electron Spin Quantum Number

~ represented by ms

~ it has values of -1/2 , 1/2 , and + or - 1/2

~ this is the direction in which an electron spin either "up" or "down"

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